The flip operations available are: left for right (-leftright or -lr); top for bottom (-topbottom or -tb); and transposition (-transpose or -xy). In addition, some canned concatenations are available: -rotate90 or -ccw is equivalent to -transpose -topbottom; -rotate270 or -cw is equivalent to -transpose -leftright; and -rotate180 is equivalent to -leftright -topbottom.
All flags can be abbreviated to their shortest unique prefix.